build: try using custom-built libstdc++

.docker/Dockerfile.alpine

@@ -12,8 +12,7 @@ RUN apk add --no-cache \
         tar \
         ripgrep \
         py3-pip \
-        less
-RUN apk add --no-cache \
+        less \
         gcc \
         g++ \
         clang18 \
@@ -50,16 +49,32 @@ RUN apk add --no-cache \
         strace \
         gdb
 
+# Install UPX
 ARG ARCH
 RUN wget -O - https://github.com/upx/upx/releases/download/v5.0.0/upx-5.0.0-$(bash -c "echo \${0//v8/}" $ARCH)_linux.tar.xz | tar -xJf - -C /usr/local/bin --strip-components=1 --wildcards "*/upx"
+
+# Install mistletoe
 RUN pip3 install --break-system-packages --root-user-action ignore mistletoe
-RUN git config --global --add safe.directory /workspace
+
+# Install size-optimized and static-link-optimized libstdc++
+RUN apk add --no-cache gmp-dev mpfr-dev mpc1-dev isl-dev
+COPY install-libstdcxx.sh /usr/local/bin/install-libstdcxx.sh
+RUN bash /usr/local/bin/install-libstdcxx.sh
+
+# Install mold
 COPY install-mold.sh /usr/local/bin/install-mold.sh
 RUN bash /usr/local/bin/install-mold.sh
+
+# Install bloaty
 COPY install-bloaty.sh /usr/local/bin/install-bloaty.sh
 RUN bash /usr/local/bin/install-bloaty.sh
+
+# Install all static libraries
 COPY install-static-libs.sh /usr/local/bin/install-static-libs.sh
 RUN bash /usr/local/bin/install-static-libs.sh gcc clang-19 :alpine
+
+# Set up git & user
+RUN git config --global --add safe.directory /workspace
 RUN adduser -G users -s bash -u 1000 -D mhx
 USER mhx
 ENTRYPOINT /workspace/.docker/build-linux.sh

.docker/build-linux.sh

@@ -254,6 +254,9 @@ if [[ "-$BUILD_TYPE-" == *-shared-* ]]; then
 fi
 
 if [[ "-$BUILD_TYPE-" == *-static-* ]]; then
+  if [[ "-$BUILD_TYPE-" == *-relsize-* ]]; then
+    LDFLAGS="${LDFLAGS} -L/opt/static-libs/libstdc++-Os/lib"
+  fi
   CMAKE_ARGS_NONSTATIC="${CMAKE_ARGS}"
   export LDFLAGS="${LDFLAGS} -L/opt/static-libs/$COMPILER/lib"
   if [[ "$ARCH" == "aarch64" ]]; then

.docker/install-libstdcxx.sh

@@ -0,0 +1,77 @@
+#!/bin/bash
+
+set -ex
+
+cd "$HOME"
+mkdir pkgs
+cd pkgs
+
+GCC_VERSION=14.2.0
+
+wget https://ftp.gwdg.de/pub/misc/gcc/releases/gcc-${GCC_VERSION}/gcc-${GCC_VERSION}.tar.xz
+tar xf gcc-${GCC_VERSION}.tar.xz
+cd gcc-${GCC_VERSION}
+
+for p in 0001-posix_memalign.patch \
+         0002-gcc-poison-system-directories.patch \
+         0003-specs-turn-on-Wl-z-now-by-default.patch \
+         0004-Turn-on-D_FORTIFY_SOURCE-2-by-default-for-C-C-ObjC-O.patch \
+         0005-On-linux-targets-pass-as-needed-by-default-to-the-li.patch \
+         0006-Enable-Wformat-and-Wformat-security-by-default.patch \
+         0007-Enable-Wtrampolines-by-default.patch \
+         0008-Disable-ssp-on-nostdlib-nodefaultlibs-and-ffreestand.patch \
+         0009-Ensure-that-msgfmt-doesn-t-encounter-problems-during.patch \
+         0010-Don-t-declare-asprintf-if-defined-as-a-macro.patch \
+         0011-libiberty-copy-PIC-objects-during-build-process.patch \
+         0012-libgcc_s.patch \
+         0013-nopie.patch \
+         0014-ada-fix-shared-linking.patch \
+         0015-build-fix-CXXFLAGS_FOR_BUILD-passing.patch \
+         0016-add-fortify-headers-paths.patch \
+         0017-Alpine-musl-package-provides-libssp_nonshared.a.-We-.patch \
+         0018-DP-Use-push-state-pop-state-for-gold-as-well-when-li.patch \
+         0019-aarch64-disable-multilib-support.patch \
+         0020-s390x-disable-multilib-support.patch \
+         0021-ppc64-le-disable-multilib-support.patch \
+         0022-x86_64-disable-multilib-support.patch \
+         0023-riscv-disable-multilib-support.patch \
+         0024-always-build-libgcc_eh.a.patch \
+         0025-ada-libgnarl-compatibility-for-musl.patch \
+         0026-ada-musl-support-fixes.patch \
+         0027-configure-Add-enable-autolink-libatomic-use-in-LINK_.patch \
+         0028-configure-fix-detection-of-atomic-builtins-in-libato.patch \
+         0029-libstdc-do-not-throw-exceptions-for-non-C-locales-on.patch \
+         0030-gdc-unconditionally-link-libgphobos-against-libucont.patch \
+         0031-druntime-link-against-libucontext-on-all-platforms.patch \
+         0032-libgnat-time_t-is-always-64-bit-on-musl-libc.patch \
+         0033-libphobos-do-not-use-LFS64-symbols.patch \
+         0034-libgo-fix-lfs64-use.patch \
+         0035-loongarch-disable-multilib-support.patch \
+         0036-libphobos-add-riscv64-and-loongarch64-support.patch \
+         fix-arm64.patch \
+         ppc64le-quadmath.patch \
+         riscv64-improve-build-time.patch; do
+    curl https://gitlab.alpinelinux.org/alpine/aports/-/raw/3.21-stable/main/gcc/$p | patch -p1
+done
+curl https://gcc.gnu.org/pipermail/gcc-patches/attachments/20250220/c6211b02/attachment.bin | patch -p1
+
+for opt in s 2; do
+    cd "${HOME}"/pkgs
+    mkdir gcc-${GCC_VERSION}-build-O${opt}
+    cd gcc-${GCC_VERSION}-build-O${opt}
+
+    export CFLAGS="-O${opt} -ffunction-sections -fdata-sections -fmerge-all-constants -fPIC"
+    export CXXFLAGS="-O${opt} -ffunction-sections -fdata-sections -fmerge-all-constants -fPIC"
+    export LDFLAGS="-Wl,--gc-sections"
+    INSTALLDIR=/opt/static-libs/libstdc++-O${opt}
+    "$HOME"/pkgs/gcc-${GCC_VERSION}/configure --prefix=${INSTALLDIR} --libdir=${INSTALLDIR}/lib \
+        --disable-shared --enable-tls --disable-libstdcxx-pch --disable-multilib --disable-nls --disable-werror --disable-symvers \
+        --enable-threads --enable-__cxa_atexit --enable-languages=c,c++ --enable-link-serialization=2 --enable-linker-build-id \
+        --disable-libssp --disable-libsanitizer --with-system-zlib --enable-checking=release --disable-cet --disable-fixed-point \
+        --enable-default-pie --enable-default-ssp
+    make -j"$(nproc)"
+    make install
+done
+
+cd "$HOME"
+rm -rf pkgs